The present invention relates to torque biasing devices and speed matching devices and methods for controlling same, in particular to torque biasing and speed matching devices having output cones, whose torque is independently adjusted by the effect of friction rings interacting with an input cone.
Common automotive differentials split torque between two different output axle shafts using a basic arrangement of pinion and side gears, driven by an input gear to split the input torque into two output torques for transmission to the wheels. This arrangement of gears does not provide for any substantial shifting, or biasing of the torque between the two wheels to meet different frictional conditions that each wheel may be experiencing. Individual wheels often experience intermittent, lower coefficients of friction caused by patches of ice, water, mud, gravel, loose dirt or broken pavement. A method of varying, or biasing the torque between two wheels can improve overall vehicle traction by providing more torque to a wheel that is gripping and less friction to a wheel that is slipping. Biasing can be accomplished using the mechanism described in this invention, combined with control strategies for detecting wheel slip well known to practitioners in the art.
Common automotive transmissions induce a lurch, or brief deceleration into the vehicle when engaging the input torque from the engine during a shift in gears. A method of matching the speeds of the engine output shaft and transmission input shaft can reduce or eliminate this lurch.
The present invention uses friction cone technology to bias torque between two separate output shafts and/or to match an output shaft speed with an input shaft speed. The basic friction cone is known from British Patent Number 298,676, and another friction cone application is known from U.S. Pat. No. 5,924,953. Additional references include the following U.S. Pat. Nos. 5,681,235; 4,957,474; 4,639,869; 3,820,408; 4,963,122; 5,688,201; 3,894,439; 4,229,985; 5597,056. All of these patents are incorporated herein by reference.
A first object and/or advantage of the invention is to provide a torque biasing device with active controls to allow the torque to be adjusted between two output shafts, as in an automobile differential.
A second object and/or advantage of the invention is to provide a speed matching device with active controls to allow the smooth matching of a driven output shaft to the speed of a driving input shaft, as in an automotive clutch matching the engine output shaft speed to the transmission input shaft speed during a clutching operation.